1. Field of the Invention
The invention relates to electrical resistors and somewhat more particularly to thin film electrical resistors and a method of producing the same.
2. Prior Art
In electrical technology, low ohmic and high ohmic layer resistors are utilized in a variety of devices. For example, such layer resistors are required in discrete resistors, in RC-networks, in thin film wire strain gauges, as resistors in integrated semiconductor circuits, etc. Known materials for layer resistors of this type include nickel-chromium, tantalum nitride (Ta.sub.2 N) and tantalum oxynitride. These materials have a relatively low ohmic resistance, for example, a nickel-chromium layer or a tantalum nitride layer exhibits a surface resistance ranging between 50 to 300 .DELTA./.quadrature. and a temperature coefficient of electrical resistance in the range of about +50 to -300 ppm/.degree.K. It is also known to use transition phase or mixtures of metals and metal oxides in forming layer resistors. It is further known to use chromium disilicide (CrSi.sub.2) as a material for layer resistors (see J. Foerster, Radio Mentor Electronic, Vol, 42, 1972, pages 342-346; I. Nishida, J. Material Science, Vol. 7, 1972 page 1119 and K. Hieber et al, Thin Solid Films, Vol, 36, 1976 pages 357-360). The specific electrical resistance of a chromium disilicide layer of this type is about 1400 .mu..OMEGA..multidot.cm and the temperature coefficient of electrical resistance thereof is in the range of about 500 to 800 ppm/.degree.K.
Known high ohmic resistors are subjected to a high failure rate on account of greatly diminished reproducibility of relevant characteristics. Accordingly, there is a need for economical high ohmic resistors which have relevant characteristics that are readily reproducible in a relatively simple and reliable manner.